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Research on quality signal development typically focuses on signals with production costs; less is known about signals that lack production costs (conventional signals). Here, I test the condition dependence and heritability of the facial patterns that function as a conventional signal of quality in Polistes dominulus wasps. Two aspects of facial patterns are compared: (1) amount of black pigment (no signal value) and (2) disruption in the black pigment's distribution (quality signal). When colonies received the same diet, they produced offspring with similar facial patterns and both traits were heritable. However, experimental diet manipulation substantially influenced quality signal development. Wasps fed unlimited caterpillars developed more disrupted facial patterns than wasps fed a restricted diet. Further, signal heritability was obscured following the diet treatment. In contrast, the nonsignaling trait was not influenced by the diet treatment and remained heritable. Overall, the quality signal in P. dominulus is condition dependent and heritable, but its heritability may be obscured by environmental variance. The nonsignaling aspect of wasp facial patterns is not condition dependent and is more consistently heritable across environments. Therefore, the information a signal conveys may be influenced by its developmental properties rather than its honesty-ensuring cost or the pigments that constitute it. [ABSTRACT FROM AUTHOR]

Presents a study which tested social contract theory in an effort to measure reproductive skew in 24 cofoundress associations of paper wasps, Polistes bellicosus. What was used to test the social contracts theory of the wasps; Problems encountered with measuring skew; Details on the social contracts models used in this study; Results of this study.

We describe new ESS models of density regulation driven by genic selection to explain the cyclical dynamics of a social system that exhibits a rock-paper-scissors (RPS) set of three alternative strategies. We tracked changes in morph frequency and fitness of Lacerta vivipara and found conspicuous RPS cycles. Morphs of Uta and Lacerta exhibited parallel survival-performance trade-offs. Frequency cycles in both species of lizards are driven by genic selection. In Lacerta, frequency of each allele in adult cohorts had significant impacts on juvenile recruitment, similar to mutualistic, altruistic, and antagonistic relations of RPS alleles in Uta. We constructed evolutionarily stable strategy (ESS) models in which adults impact juvenile recruitment as a function of self versus nonself color recognition. ESS models suggest that the rapid 4-year RPS cycles exhibited by Lacerta are not possible unless three factors are present: behaviors evolve that discriminate self versus nonself morphs at higher rates than random, self- versus non-self-recognition contributes to density regulation, and context-dependent mate choice evolves in females, which choose sire genotypes to enhance progeny survival. We suggest genic selection coupled to density regulation is widespread and thus fundamental to theories of social system evolution as well as theories of population regulation in diverse animal taxa. [ABSTRACT FROM AUTHOR]

The production schedules of males and reproductive females by the foundress queens and the ratios of parental investment in males and reproductive females (investment sex ratios) of successful colonies are compared for several temperate and subtropical paper wasps. The production schedules are classified into three types: males and reproductive females are produced simultaneously (simultaneous production), males are produced before reproductive females (protandrous production), and reproductive females are produced before males (protogynous production). The investment sex ratios for various species vary from about parity to a strong predominance of females. But significant combinations of the production-schedule type and the magnitude of the investment ratio are found. In four species with simultaneous production, the investment ratios are about 1:1. In five species with protandrous production, the ratio is more than 4:1, except for one species, for which the investment ratio seems to be underestimated. In three species with protogynous production, the female bias is moderate in two species and strong in one. The possible causes leading to these results are discussed. This study shows the error of using a single explanation for the investment sex ratios of annual paper wasps and the importance of a close examination of the social system of each species. [ABSTRACT FROM AUTHOR]

Research on individual recognition often focuses on speciestypical recognition abilities rather than assessing intraspecific variation in recognition. As individual recognition is cognitively costly, the capacity for recognition may vary within species. We test how individual face recognition differs between nest-founding queens (foundresses) and workers in Polistes fuscatus paper wasps. Individual recognition mediates dominance interactions among foundresses. Three previously published experiments have shown that foundresses (1) benefit by advertising their identity with distinctive facial patterns that facilitate recognition, (2) have robust memories of individuals, and (3) rapidly learn to distinguish between face images. Like foundresses, workers have variable facial patterns and are capable of individual recognition. However, worker dominance interactions are muted. Therefore, individual recognition may be less important for workers than for foundresses. We find that (1) workers with unique faces receive amounts of aggression similar to those of workers with common faces, indicating that wasps do not benefit from advertising their individual identity with a unique appearance; (2) workers lack robust memories for individuals, as they cannot remember unique conspecifics after a 6-day separation; and (3) workers learn to distinguish between facial images more slowly than foundresses during training. The recognition differences between foundresses and workers are notable because Polistes lack discrete castes; foundresses and workers are morphologically similar, and workers can take over as queens. Overall, social benefits and receiver capacity for individual recognition are surprisingly plastic. [ABSTRACT FROM AUTHOR]

A major bottleneck in the time required to publish a scientific or scholarly paper is the speed with which reviews by peers are returned to journals. Peer review is a reciprocal altruistic system in which each individual may perform every task--editors, reviewers, and authors--at different times. Journals have no way to coerce reviewers to return their critiques faster. To greatly shorten the time to publication, all actors in this altruistic network should abide by the Golden Rule of Reviewing: review for others as you would have others review for you. Say yes to reviewing whenever your duties and schedule allow; provide a thorough, fair, and constructive critique of the work; and do it at your first opportunity regardless of the deadline. [ABSTRACT FROM AUTHOR]

The author looks forward to defining the scope of the journal as he settles to the role of editor. He argues on the publication of articles on topics including genomics, immunology and neurobiology that can help in understanding evolution and ecology. He expresses his intention to look into other means of communicating data and results to readers such as animated or interactive graphics, as well as ideas for improving the speed and efficacy of peer review.

The article presents an announcement regarding various research papers published in the February 2004 issue of the journal "American Naturalist." the journal is taking this course for three reasons, scientific publishing is changing rapidly, electronic publishing is taking larger role, the advent of electronic publishing is radically changing its way in which scientific way can be communicated. There are advantages to the publishing articles electronically because such papers will be freely available to anyone on the Internet.

The article presents information about several awards presented by the American Society of Naturalists. The President's award of the American Society of Naturalists is given to the best paper that appeared in the journal "American Naturalist" in the preceding calendar year. The Edward Osborne Wilson Naturalist Award was established in 1997 on the occasion of Professor Wilson's retirement in recognition of his lifetime of outstanding contributions in the areas of ecology and evolutionary biology, including the study of social insects, biodiversity, and biophilia. The Sewall Wright Award, which recognizes a senior-level active researcher for significant and continuing contributions to the objectives of the American Society of Naturalists, was awarded in 2005 to Robert E. Ricklefs. The Young Investigators' Prizes recognize outstanding and promising work by investigators who received their doctorates in the three years preceding the application deadline or are in their final year of graduate school. The prizes include presentation of a research paper at the annual meeting of the American Society of Naturalists, reimbursement for travel to the annual meeting, and a $500 honorarium.

Although there has been much experimental work on floral traits that are under selection from mutualists and antagonists, selection by abiotic environmental factors on flowers has been largely ignored. Here we test whether pollen susceptibility to rain damage could have played a role in the evolution of the reproductive architecture of Davidia involucrata, an endemic in the mountains of western China. Flowers in this tree species lack a perianth and are arranged in capitula surrounded by large (up to 10 cm) bracts that at anthesis turn from green to white, losing their photosynthetic capability. Flowers are nectarless, and pollen grains are presented on the recurved anther walls for 5-7 days. Flower visitors, and likely pollinators, were mainly pollen-collecting bees from the genera Apis, Xylocopa, Halictus, and Lasioglossum. Capitula with natural or white paper bracts attracted significantly more bees per hour than capitula that had their bracts removed or replaced by green paper. Experimental immersion of pollen grains in water resulted in rapid loss of viability, and capitula with bracts lost less pollen to rain than did capitula that had their bracts removed, suggesting that the bracts protect the pollen from rain damage as well as attracting pollinators. [ABSTRACT FROM AUTHOR]

A recent paper by Richard McGarvey, Natalie Dowling, and Joel E. Cohen, "Longer Food Chains in Pelagic Ecosystems: Trophic Energetics of Animal Body Size and Metabolic Efficiency," appearing in the July 2016 issue of The American Naturalist, reinstated the importance of energetics for explaining variation in food chain length. Using an allometric model, they deduce that smaller body sizes and a higher proportion of ectotherms could explain why pelagic ecosystems have longer food chains, despite relatively low primary productivity. In this paper, I argue that their proposed mechanism underlying the body size effect--based on more rapid energy transfers-- could not be sustained under more realistic ecological constraints. This makes the metabolic efficiency of ectotherms a more plausible explanation for the observed patterns of food chain length. [ABSTRACT FROM AUTHOR]

The article comments on the study "Detecting population differences in quantitative characters as opposed to gene frequencies" by R. C. Lewontin in the 1984 issue and on the study " Population differences in quantitative characters as opposed to gene frequencies" by A. R. Rogers in the 1986 issue. Topics include Lewontin and Rogers stated to differ in what their formulas imply about testing quantitative characters versus gene frequencies, and the omission of a calculation of the variances.

The article discusses the evolutionary and ecological aspects of leaf emergence. The author highlights the study published by biologist Martin Lechowicz which seeks to understand t the factors affecting the emergence of leaves in deciduous plants, and notes the influence of climatic changes in the leafing of trees.

The article announces that Jane Lubchenco has been awarded with the Honorary Lifetime Membership award by the American Society of Naturalists.

The article focuses on the evolution of Flowering time and discusses the significance of flowering times of plant species. Topics discussed includes ancestral seasonal flowering phenologies, the synchrony between flowering and humming bird migration and effects of phylogenetic signal and adaptation to local conditions.

Intransitive competition has received much attention over the past decade. Indeed, these cyclic arrangements of species interactions have the potential to promote and stabilize species coexistence. However, the importance of intransitive interactions in real-world species-rich communities containing a mixture of hierarchic and intransitive interactions remains unknown. Here, using simulations, we explore the behavior of intransitive loops when they interact with outer competitors, as would be expected in real-world communities. Our results show that dominant competitors often cancel the beneficial effects of intransitive loops of inferior competitors. These results call for caution when inferring beneficial effects of intransitivity on species coexistence. Although intransitive loops are a frequent motif in competition networks, their positive effects on species coexistence may be less important than previously thought. The specific properties of a subnetwork—such as stabilization by intransitive loops—should thus not be interpreted independently of the global network. [ABSTRACT FROM AUTHOR]

The article offers information on several reports presented during the American Society of Naturalists (ASN) Executive Council Meeting held in Snowbird, Utah on June 21-25, 2013. ASN president Dolph Schluter reported on a memorandum of understanding (MOU) between the University of Chicago Press (UCP) and ASN. Treasurer Catherine Graham's report that ASN is making profit. Secretary's report focused on election of president and vice president of ASN.

The article discusses papers published in the issue, including one by Shemske on Charles Darwin's views on speciation, one by Pfennig and Pfennig on Darwin's concept of adaptive divergence and how it affects species coexistence, and one by Presgraves on Darwin's discussion of hybrid sterility.

Models are universal in science, both as theoretical formulations of reality and as model systems, representatives of other organisms. A recent paper on how scientists view the world divides our work into the mind, the lab, and the field and suggests that models must not be conflated with reality. But in practice, these distinctions are blurred. For example, are flour beetles a model system for other insects when their natural habitat is the same as the way they live in the lab? In addition, models can become restrictive when they are viewed as archetypes, making us overgeneralize about the world and ignoring meaningful variation. The study of sexual conflict in insects illustrates some of the pitfalls of relying on Drosophila as a model system for sexual selection. Microbes can be used as models for populations and communities and are essential parts of larger biological systems. Finally, some models are not meant to replicate the world but are worlds unto themselves in which diverse possibilities can be directly observed. [ABSTRACT FROM AUTHOR]

Intransitive (or "rock-paper-scissors") competition is compelling because it promotes species coexistence and because recent work suggests that it may be common in natural systems. One class of intransitivity indices works by considering s, the minimum number of competitive reversals to convert a given competitive community (i.e., a "tournament") to a hierarchy. The most straightforward example of such "reversal-based" indices is Petraitis's index, t p 1 2 s=M, where M is the maximum s across all possible n-species tournaments. Using exhaustive searches, we prove that Petraitis's formula for M (and, therefore, t) does not hold for n ≥ 7. Furthermore, determination of s for even moderate values of n may prove difficult, as the equivalent graph theoretical problem is NP (nondeterministic polynomial time) hard; there is no known computationally feasible way to compute an exact answer for anything but small values of n, let alone a closed-form solution. Petraitis's t is a valuable index of intransitivity; however, at present its use is limited to relatively speciespoor systems. More broadly, reversal-based indices, while intuitive, may be problematic because of this computability issue. [ABSTRACT FROM AUTHOR]

Simulations and experiments have shown that species coexistence can be maintained via nontransitive competition, of which a simple case is the rock-paper-scissors game. Reef-building corals exemplify high biodiversity competing for a few limiting resources via several mechanisms. Thus, corals represent fertile ground for exploring competition and nontransitivity. This article aimed to test hypotheses about the effects of species-level traits on competitive outcomes, specifically, that more upright growth, larger corallites, smaller ranges, and difference in commonness co-occur with competitive superiority. Further aims were to test whether closely related species show less predictable competitive outcomes and greater nontransitivity and to examine the level of nontransitivity among a large number of species. These goals were addressed by fitting a mixed-effects model to outcomes of 2,322 interspecific interactions. Among species-level traits, corallite width had the greatest impact on outcome, followed by geographical range size, growth form, and the typical commonness of conspecifics in assemblages. These fixed effects had smaller estimated impacts than a random effect associated with species pair, suggesting a primary role for idiosyncratic species-pair or other factors. Closely related species hadmore variable, less predictable interaction outcomes. Nearly a quarter of three-way species relations were nontransitive. The observed degree of competitive nontransitivity and extent of idiosyncratic species-pair effects together provide an empirical baseline for further investigations of mechanisms of species coexistence. [ABSTRACT FROM AUTHOR]

The article provides updates on the American Society of Naturalists (ASN). Stevan Arnold was elected president and will serve from 2011 to 2015. He will consequently be joined by Hopi Hoekstra as his vice president from 2011 to 2013. Kate Boersma is stepping down as the ASN graduate student representative, however, the appointment for her successor is unclear.

Predation risk has long been known to exert a strong influence on behavior, but no study to date has determined whether predators influence offspring antipredator behavior via maternal effects. Here, we provide a unique example of a transgenerational maternal effect in antipredator behavior that takes the form of a "warning" about predators that female fall field crickets Gryllus pennsylvanicus transmit to their offspring. Specifically, the offspring of gravid crickets exposed to a wolf spider Hogna helluo exhibit greater antipredator immobility in response to Hogna chemical cues than do offspring of nonexposed females. These "forewarned" crickets exhibit greater survival in the presence of Hogna than do those not forewarned. Accordingly, gravid crickets from areas with significant Hogna populations produce offspring that are more responsive to Hogna cues than do those from nearby Hogna-free areas. Such transgenerational maternal effects may be more common than currently realized. [ABSTRACT FROM AUTHOR]

The article announces two awards given by the American Society of Naturalists to scientists including the Sewall Wright Award to biologist Dolph Schluter and the E. O. Wilson Award to ecologist Trevor Price.

The article reports on the activities that happened in 2006 for the American Society of Naturalists. The executive meeting held June 23, 2006 emphasized on the success of the three-editor system and electronic papers of the society's publication. The business meeting of the society focused on the presentation of the anti-wedge document to the Joint Council, which establishes medium-term and long-term goals to defend and promote the teaching of evolutionary biology. The next meeting of the joint committee pointed on the support of the Joint Council to the anti-wedge document.

The article presents information about the report presented by Judith Bronstein, who succeeded Timothy Wootton as American Society of Naturalists (ASN) secretary in January 2004. Subsequent activities were focused on conducting the annual election. Voting instructions were sent out electronically, and paper ballots were mailed on April 16, 2004. On the deadline, May 20, 2004, 255 electronic ballots and eight mail ballots were counted. The other major secretarial activity consisted of updating the ASN web site, which had fallen significantly out of date.

The article discusses a set of papers written by U.S. entomologist Charles T. Brues in the 1920s published in the journal on the evolution of dietary specialization in insects. It cites several issues tackled by Brues in his papers such as the occurrence of parallel evolution. It also mentions Brues' concern about the decline in knowledge of the natural history of species and interactions in biological training and research.

“Food Web Complexity and Species Diversity” (Paine 1966) is the most-cited empirical article published in the American Naturalist. In short, Paine removed predatory sea stars (Pisaster ochraceus) from the rocky intertidal and watched the key prey species, mussels (Mytilus californianus), crowd out seven subordinate primary space-holding species. However, because these mussels are a foundational species, they provide three-dimensional habitat for over 300 associated species inhabiting the mussel beds; thus, removing sea stars significantly increases community-wide diversity. In any case, most ecologists cite Paine (1966) to support a statement that predators increase diversity by interfering with competition. Although detractors remained skeptical of top-down effects and keystone concepts, the paradigm that predation increases diversity spread. By 1991, “Food Web Complexity and Species Diversity” was considered a classic ecological paper, and after 50 years it continues to influence ecological theory and conservation biology. [ABSTRACT FROM AUTHOR]

W. Scott Persons IV and John Acorn, in their paper "A Sea Scorpion's Strike: New Evidence of Extreme Lateral Flexibility in the Opisthosoma of Eurypterids," appearing in the July 2017 issue of The American Naturalist, suggested a radical new mode of hunting for eurypterids involving extreme lateral flexibility that permitted the telson to slash and stab at prey, implying that eurypterids were better armed than previously supposed. Here, we show that the interpretation is based on a molt that is strongly curved because of taphonomic processes and does not reflect trunk flexibility in life. Hydrodynamic considerations reveal that the telson was not suitable for rapid lateral movement, confirming that the eurypterid telson functioned in aiding balance and generating lift during locomotion, not as a weapon. [ABSTRACT FROM AUTHOR]

The article discusses the 150th anniversary of publication of the periodical "The American Naturalist" in 2017. Topics discussed include papers published in biology, astronomy and anthropology by the periodical; development and publications of the journal and articles from scholars in the fields of evolution, ecology, and genetics that was appeared in previous issue of the journal.

The article announces that Richard Lenski has received the 2012 Sewall Wright Award from the American Society of Naturalists.

The comparative method has long been a fundamental exploratory tool in evolutionary biology, but this venerable approach was revolutionized in 1985, when Felsenstein published "Phylogenies and the Comparative Method" in The American Naturalist. This article forced comparative biologists to start thinking phylogenetically when conducting statistical analyses of correlated trait evolution rather than simply applying conventional statistical methods that ignore evolutionary relationships. It did so by introducing a novel analytical method (phylogenetically "independent contrasts") that required a phylogenetic topology with branch lengths and that assumed a Brownian motion model of trait evolution. Independent contrasts enabled comparative biologists to avoid the statistical dilemma of nonindependence of species values, arising from shared ancestry, but came at the cost of needing a detailed phylogeny and of accepting a specific model of character change. Nevertheless, this article not only revitalized comparative biology but even encouraged studies aimed at estimating phylogenies. Felsenstein's characteristically lucid and concise statement of the problem (illustrated with powerful graphics), coupled with an oncoming flood of new molecular data and techniques for estimating phylogenies, led Felsenstein's 1985 article to become the second most cited article in the history of this journal. Here we present a personal review of comparative biology before, during, and after Joe's article. For historical context, we append a perspective written by Joe himself that describes how his article evolved, unedited transcripts of reviews of his submitted manuscript, and a guide to some nontrivial calculations. These additional materials help emphasize that the process of science does not always occur gradually or predictably. [ABSTRACT FROM AUTHOR]

This article reports that the 2005 Sewall Wright Award has been given to Robert E. Ricklefs, Curators' professor of Biology at University of Missouri, Saint Louis, Missouri. Ricklefs's early comparative analyses of growth and development in both precocial and altricial birds are now the classic studies of those subjects. His continuing series of papers on the life histories of birds in relation to their demography has led to several generalizations about their evolution at broad geographic scales. Ricklefs has also been at the forefront of putting history back into community ecology ever since his widely quoted 1987 paper in Science. He used comparisons among regions to demonstrate remarkable examples in which communities have failed to converge, thus showing that community structure cannot be entirely attributed to local processes such as competition. He is also the author of two highly regarded ecology textbooks, "Ecology," which is now in its fourth edition, and "The Economy of Nature," now in its fifth edition.

The article discusses the author's experience as a graduate student in which they were taught on the subject of evolutionary biology. Topics discussed include the authors van Noordwijk and de Jong's 1986 article in "The American Naturalist", the author's trivial but real fact about heterogeneity across individual and the decades of research in evolutionary ecology.

The article presents the report of the American Society of Naturalists (ASN)Secretary in 2009. It mentions that the society will conduct its annual election for its new set of officers such as president, vice-president, and secretary on March 12, 2009. It states that recording the committee membership, updating the ASN's website, and updating the ASN Officer's handbook are the major task of the secretary of the society. It notes that Robert Ricklefs has been elected as president, David Reznick as vice-president, and Daniel Bolnick as secretary in 2010. It also presents the minutes of the ASN executive committee meeting in Moscow, Idaho from June 19-16, 2009.

We assessed genetic factors on progeny dispersal due to sire color morph genotypes in a field pedigree and lab crosses, and we measured maternal effects by studying both natural and experimentally induced egg size variation. Progeny were released into nature upon hatching, but we recorded dispersal distance at maturity, which reflects effective dispersal after viability selection has run its course. Progeny dispersal was significantly affected by sire genotype. Progeny from orange sires dispersed the farthest. Progeny from blue sires dispersed intermediate distances. Progeny from yellow sires were the most philopatric. Sire genotype effects interacted with egg size. In particular, enlarged progeny from orange sires dispersed farther, while enlarged progeny from yellow sires were more philopatric. Progeny from blue sires were unaffected by egg size manipulations. Egg manipulations and natural variation generally had concordant effects indicative of causation. However, asymmetry of gigantization and miniaturization on progeny dispersal from some sire genotypes suggest the involvement of maternal factors besides egg size. Results of laboratory crosses with progeny released into nature confirmed key sire genotype effects and identified additional maternal effects that modulated dispersal as a function of progeny gender. We discuss the adaptive implications of progeny dispersal in the context of male (rock-paper-scissors) and female strategies (r- and K-density cycle) that are associated with color morphs. [ABSTRACT FROM AUTHOR]

Recent theory suggests that much of the wide variation in individual behavior that exists within cooperative animal societies can be explained by variation in the future direct component of fitness, or the probability of inheritance. Here we develop two models to explore the effect of variation in future fitness on social aggression. The models predict that rates of aggression will be highest toward the front of the queue to inherit and will be higher in larger, more productive groups. A third prediction is that, in seasonal animals, aggression will increase as the time available to inherit the breeding position runs out. We tested these predictions using a model social species, the paper wasp Polistes dominulus. We found that rates of both aggressive ‘displays’ (aimed at individuals of lower rank) and aggressive ‘tests’ (aimed at individuals of higher rank) decreased down the hierarchy, as predicted by our models. The only other significant factor affecting aggression rates was date, with more aggression observed later in the season, also as predicted. Variation in future fitness due to inheritance rank is the hidden factor accounting for much of the variation in aggressiveness among apparently equivalent individuals in this species. [ABSTRACT FROM AUTHOR]

A model of species interactions based on their use of shared resources was proposed in 1972 by Robert MacArthur and later expanded in an article (1980) and a book (1982) by David Tilman. This ‘resource-ratio theory’ has been used to make a number of testable predictions about competition and community patterns. We reviewed 1,333 papers that cite Tilman's two publications to determine whether predictions of the resource-ratio theory have been adequately tested and to summarize their general conclusions. Most of the citations do not directly test the theory: only 26 studies provide well-designed tests of one or more predictions, resulting in 42 individual tests of predictions. Most of these tests were conducted in the laboratory or experimental microcosms and used primary producers in freshwater systems. Overall, the predictions of the resource-ratio theory were supported 75% of the time. One of the primary predictions of the model, that species dominance varies with the ratio of resource availabilities, was supported by 13 of 16 tests, but most other predictions have been insufficiently tested. We suggest that more experimental work in a variety of natural systems is seriously needed, especially studies designed to test predictions related to resource supply and consumption rates. [ABSTRACT FROM AUTHOR]

Ecological and evolutionary processes underlying spatial variation in signals involved in mate recognition and reproductive isolation are crucial to understanding the causes of population divergence and speciation. Here, to test hypotheses concerning the causes of song divergence, we examine how songs of two sister species of Atlantic Forest suboscine birds with innate songs, the Pyriglena fire-eye antbirds, vary across their ranges. Specifically, we evaluated the influence of isolation by distance and introgressive hybridization, as well as morphological and environmental variation, on geographic variation in male songs. Analyses based on 496 male vocalizations from 63 locations across a 2,200-km latitudinal transect revealed clinal changes in the structure of songs and showed that introgressive hybridization increases both the variability and the homogenization of songs in the contact zone between the two species. We also found that isolation by distance, morphological constraints, the environment, and genetic introgression independently predicted song variation across geographic space. Our study shows the importance of an integrative approach that investigates the roles of distinct ecological and evolutionary processes that influence acoustic signal evolution. [ABSTRACT FROM AUTHOR]

The arrival order of species frequently determines the outcome of their interactions. This phenomenon, called the priority effect, is ubiquitous in nature and determines local community structure, but we know surprisingly little about how it influences biodiversity across different spatial scales. Here, we use a seasonal metacommunity model to show that biodiversity patterns and the homogenizing effect of high dispersal depend on the specific mechanisms underlying priority effects. When priority effects are driven only by positive frequency dependence, dispersal-diversity relationships are sensitive to initial conditions but generally show a hump-shaped relationship: biodiversity declines when dispersal rates become high and allow the dominant competitor to exclude other species across patches. When spatiotemporal variation in phenological differences alters species' interaction strengths (trait-dependent priority effects), local, regional, and temporal diversity are surprisingly insensitive to variation in dispersal, regardless of the initial numeric advantage. Thus, trait-dependent priority effects can strongly reduce the effect of dispersal on biodiversity, preventing the homogenization of metacommunities. Our results suggest an alternative mechanism that maintains local and regional diversity without environmental heterogeneity, highlighting that accounting for the mechanisms underlying priority effects is fundamental to understanding patterns of biodiversity. [ABSTRACT FROM AUTHOR]

Many species gain antipredator benefits by combining gregarious behavior with warning coloration, yet there is debate over which trait evolves first and which is the secondary adaptive enhancement. Body size can also influence how predators receive aposematic signals and potentially constrain the evolution of gregarious behavior. To our knowledge, the causative links between the evolution of gregariousness, aposematism, and larger body sizes have not been fully resolved. Here, using the most recently resolved butterfly phylogeny and an extensive new dataset of larval traits, we reveal the evolutionary interactions between important traits linked to larval gregariousness. We show that larval gregariousness has arisen many times across butterflies, and aposematism is a likely prerequisite for gregariousness to evolve. We also find that body size may be an important factor for determining the coloration of solitary, but not gregarious, larvae. Additionally, by exposing artificial larvae to wild avian predation, we show that undefended, cryptic larvae are heavily predated when aggregated but benefit from solitariness, whereas the reverse is true for aposematic prey. Our data reinforce the importance of aposematism for gregarious larval survival while identifying new questions about the roles of body size and toxicity in the evolution of grouping behavior. [ABSTRACT FROM AUTHOR]

Many potential mechanisms promote species coexistence, but we know little about their relative importance. To compare multiple mechanisms, we modeled a two-trophic planktonic food web based on mechanistic species interactions and empirically measured species traits. We simulated thousands of possible communities under realistic and altered interaction strengths to assess the relative importance of three potential drivers of phytoplankton and zooplankton species richness: resource-mediated coexistence mechanisms, predator-prey interactions, and trait trade-offs. Next, we computed niche and fitness differences of competing zooplankton to obtain a deeper understanding of how these mechanisms determine species richness. We found that predator-prey interactions were the most important driver of phytoplankton and zooplankton species richness and that large zooplankton fitness differences were associated with low species richness, but zooplankton niche differences were not associated with species richness. However, for many communities we could not apply modern coexistence theory to compute niche and fitness differences of zooplankton because of conceptual issues with the invasion growth rates arising from trophic interactions. We therefore need to expand modern coexistence theory to fully investigate multitrophic-level communities. [ABSTRACT FROM AUTHOR]